A judge has removed one of three Republican candidates from the ballot in a hotly contested South Bay congressional race without addressing the most explosive allegation in the case - a Republican official's claim that last-minute entrants were stage-managed by Democrat Ro Khanna to smooth his path toward the November runoff.

Khanna, a former Obama administration trade representative and a moderate funded by Silicon Valley businesses, is challenging liberal seven-term Democratic Rep. Mike Honda in the 17th Congressional District. Stanford physician Vanila Singh was the sole Republican entrant until two more candidates, attorney Vinesh Rathore and tech recruiter Joel VanLandingham, filed papers just before the deadline.

The new candidacies appeared likely to split the Republican vote in the majority-Democratic district and improve Khanna's chances of finishing first or second in the June 3 primary, advancing him to a probable November runoff against Honda under California's top-two primary system. In a lawsuit seeking to disqualify both Rathore and VanLandingham, Jeffrey Wald, a member of the Alameda County Republican Central Committee, alleged that Khanna had been recruiting Republican candidates for that purpose.

Specifically, Wald said, one man who gathered signatures for VanLandingham's candidacy had previously signed a petition to put Khanna on the ballot, and allegedly told those signing papers for VanLandingham that they would actually be helping Khanna.

The allegations were presented Wednesday to a Sacramento County Superior Court judge, Allen Sumner. In a brief ruling, he ordered Rathore removed from the ballot, finding that at least one of the 40 signatures his campaign submitted - the exact minimum number required - was invalid.

Sumner did not remove VanLandingham, finding his signatures valid. According to an account in the Recorder, a legal newspaper, the judge told attorneys that no state law prohibited a supporter of one candidate from circulating papers for another, and said he needed something more than "public policy arguments" to disqualify a candidate.

Khanna's campaign said it had been vindicated.

"Launching baseless attacks that smear an opponent is the kind of politics that Ro is fighting to change," campaign manager Leah Cowan said in a statement. "Fortunately, the legal system worked, the allegations were dismissed and the case is now closed."

Not so, said Harmeet Dhillon, vice chairwoman of the state Republican Party and a law partner of Wald's attorney in the court case. She said the tactics alleged in the suit are, if proven, a legal basis for overturning the results of an election.